need help for vfo

kumar gautam

hi,

in my bitx20 vfo frequency is 4.000 to 4.230MHz or trimming the trimmer i found 4.200 to 4.430 (i.e 0 to 0.230 MHz tuning range).?aftyer several changing in coil and various types of capacitor(2j or 2x type) i coul'd not achive the desired frequency. i used 2n2222a transistors for VFO and BFO and for rest 2n3904.

kindly anyone help me in this regard?

with 73's

de kumar gautam

Free antispam, antivirus and 1GB to save all your messages
Only in Yahoo! Mail: http://in.mail.yahoo.com

ajparent1

#921

Hello,

First the transistor used.  The 2n222a or 2n3904 are excellent for
this type VFO.

I have tried to understand what problem you are having.  I suspect 
the range of tuning 0-230khz is either too small or too great for
you.  The ability to adjust the frequency using the trimmer says 
the coil and other components are close.  

Allison
KB1GMX


--- In BITX20@..., kumar gautam <fromgautam@y...> wrote:
hi,
in my bitx20 vfo frequency is 4.000 to 4.230MHz or trimming thetrimmer i found 4.200 to 4.430 (i.e 0 to 0.230 MHz tuning range).
aftyer several changing in coil and various types of capacitor(2j or
2x type) i coul'd not achive the desired frequency. i used 2n2222a
transistors for VFO and BFO and for rest 2n3904.
kindly anyone help me in this regard 
with 73's
de kumar gautam

		
---------------------------------
 Free antispam, antivirus and 1GB to save all your messages
 Only in Yahoo! Mail: 

#922

Hi,
I think the tuning range is found to be to small.
Likely because the tuning capacitor does not have enough capacitance.
(the LC combination defines the frquency and if the L is fixed, only 
the C can be responsible?).
If there are more capacitors inside the housing, just connect them 
also. Otherwise an other type of capacitor is needed.
An other possibility is to have the range in two bands, by switching 
an additional capacitor in parallel.
Regards,
Chris.

--- In BITX20@..., "ajparent1" <kb1gmx@a...> wrote:
Hello,

First the transistor used.  The 2n222a or 2n3904 are excellent for
this type VFO.

I have tried to understand what problem you are having.  I suspect 
the range of tuning 0-230khz is either too small or too great for
you.  The ability to adjust the frequency using the trimmer says 
the coil and other components are close.  

Allison
KB1GMX


--- In BITX20@..., kumar gautam <fromgautam@y...> wrote:
hi,
in my bitx20 vfo frequency is 4.000 to 4.230MHz or trimming thetrimmer i found 4.200 to 4.430 (i.e 0 to 0.230 MHz tuning range).
aftyer several changing in coil and various types of capacitor(2j or
2x type) i coul'd not achive the desired frequency. i used 2n2222a
transistors for VFO and BFO and for rest 2n3904.
kindly anyone help me in this regard 
with 73's
de kumar gautam

		
---------------------------------
 Free antispam, antivirus and 1GB to save all your messages
 Only in Yahoo! Mail: 

ajparent1

#926

Hi Chris,

Rather than guess at Gautams question it is easy to ask. Saves 
giving multiple conflicting answers.

I may add my favorite "cheap" Varactor [tuning] diode is 1n4007
rectifier.  It also makes a fair substitute for a PIN diode
in switches and attenuators. Not as good as the real thing but
far less cost.


Allison
KB1GMX

Show quoted text

--- In BITX20@..., "vdberghak" <vdberghak@z...> wrote:
Hi,
I think the tuning range is found to be to small.
Likely because the tuning capacitor does not have enough capacitance.
(the LC combination defines the frquency and if the L is fixed, only 
the C can be responsible?).
If there are more capacitors inside the housing, just connect them 
also. Otherwise an other type of capacitor is needed.
An other possibility is to have the range in two bands, by switching 
an additional capacitor in parallel.
Regards,
Chris.

--- In BITX20@..., "ajparent1" <kb1gmx@a...> wrote:
Hello,

First the transistor used.  The 2n222a or 2n3904 are excellent for
this type VFO.

I have tried to understand what problem you are having.  I suspect 
the range of tuning 0-230khz is either too small or too great for
you.  The ability to adjust the frequency using the trimmer says 
the coil and other components are close.  

Allison
KB1GMX


--- In BITX20@..., kumar gautam <fromgautam@y...> wrote:
hi,
in my bitx20 vfo frequency is 4.000 to 4.230MHz or trimming thetrimmer i found 4.200 to 4.430 (i.e 0 to 0.230 MHz tuning range).
aftyer several changing in coil and various types of capacitor(2j or
2x type) i coul'd not achive the desired frequency. i used 2n2222a
transistors for VFO and BFO and for rest 2n3904.
kindly anyone help me in this regard 
with 73's
de kumar gautam

		
---------------------------------
 Free antispam, antivirus and 1GB to save all your messages
 Only in Yahoo! Mail: 

开云体育

need help for vfo